在LINQ to Entities中选择多列时出现无效的匿名类型错误

本文关键字：无效 错误 类型 Entities to LINQ 选择 | 更新日期: 2023-09-27 18:24:43

我正试图从几个不同的LINQ查询填充我的ViewModel，但我遇到了从一个LINQ查询中填充多个属性的问题，但我得到了错误

无效的匿名类型成员声明符。匿名类型成员必须用成员分配、简单名称或成员访问声明

我做了一些搜索，找到了一些帖子，但它们都是关于完全填充ViewModel，而不仅仅是像我试图做的一些属性。我应该怎么做才能解决这个问题，还是我完全错了？

using (ForumContext db = new ForumContext())
{
    model.ID = db.yaf_Topic
                .Where(t => t.ForumID == 5)
                .OrderByDescending(t => t.Posted)
                .Select(t => t.PollID.Value).First();
    model = db.yaf_Poll
                .Where(p => p.PollID == model.ID)
                .Select(p => new
                {
                    model.Question = p.Question,
                    model.IsMultipleChocie = p.AllowMultipleChoices,
                    model.ExperationDate = p.Closes
                })
                .First();
    model.Choices = db.yaf_Choice
                        .Where(c => c.PollID == model.ID)
                        .Select(c => new
                        {
                            model.Votes.Key = c.Choice,
                            model.Votes.Value = c.Votes,
                        })
                        .ToList();
    model.VotedIPs = db.yaf_PollVote
                        .Where(p => p.PollID == model.ID)
                        .Select(p => p.RemoteIP)
                        .ToList();
    model.VotedUserIDs = db.yaf_PollVote
                            .Where(p => p.PollID == model.ID)
                            .Select(p => p.UserID)
                            .ToList();
}

我的型号：

public class PollVM
{
    public int ID { get; set; }
    public string Question { get; set; }
    public bool IsMultipleChocie { get; set; }
    public DateTime? ExperationDate { get; set; }
    public KeyValuePair<string, int> Choices { get; set; }
    public List<string> VotedIPs { get; set; }
    public List<int?> VotedUserIDs { get; set; }
}

在LINQ to Entities中选择多列时出现无效的匿名类型错误

不能在匿名类型声明中分配变量。您需要首先选择匿名类型变量，并将其属性逐一分配给模型属性。更改此部件

model = db.yaf_Poll
            .Where(p => p.PollID == model.ID)
            .Select(p => new
            {
                model.Question = p.Question,
                model.IsMultipleChocie = p.AllowMultipleChoices,
                model.ExperationDate = p.Closes
            })
            .First();

到这个

var poll = db.yaf_Poll
            .Where(p => p.PollID == model.ID)
            .Select(p => new
            {
                p.Question,
                p.AllowMultipleChoices,
                p.Closes
            })
            .First();
model.Question = poll.Question;
model.IsMultipleChocie = poll.AllowMultipleChoices;
model.ExperationDate = poll.Closes;

下面的第三个查询有相同的问题

model.Choices = db.yaf_Choice
                    .Where(c => c.PollID == model.ID)
                    .Select(c => new
                    {
                        model.Votes.Key = c.Choice,
                        model.Votes.Value = c.Votes,
                    })
                    .ToList();

我想可能有不止一种选择，所以把你的型号改为

public class PollVM
{
    public PollVM()
    {
        this.Choices = new List<KeyValuePair<string, int>>();
    }
    public int ID { get; set; }
    public string Question { get; set; }
    public bool IsMultipleChocie { get; set; }
    public DateTime? ExperationDate { get; set; }
    public List<KeyValuePair<string, int>> Choices { get; set; }
    public List<string> VotedIPs { get; set; }
    public List<int?> VotedUserIDs { get; set; }
}

并将第三个查询更改为该

var choices = db.yaf_Choice
                    .Where(c => c.PollID == model.ID)
                    .Select(c => new
                    {
                        c.Choice,
                        c.Votes,
                    })
                    .ToList();
foreach (var ch in choices)
{
    model.Choices.Add(new KeyValuePair<string, int>(ch.Choice, ch.Votes));
}
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